Mode Analyses of Subwavelength Periodic Metallic Structures With Finite Thickness

Deep-subwavelength periodic metallic structures, which are also called plasmonic metamaterials, have received much attention due to their ability of supporting spoof surface plasmons polariton (SPP) modes. However, it is still difficult to obtain the dispersion relations of different modes for complicated plasmonic metamaterials with finite thickness. To solve the problem, we make further development of a field-network joint dispersion analysis method that was proposed recently so that the method can be used to analyze the spoof SPP structures with a certain thickness. The developed method not only allows us to predict the dispersion relations of complicated spoof SPP structures with finite thickness but also can be used to find a series of intrinsic high-order modes of the periodic metallic structures. As an example, we present the theoretical dispersion curves of the fundamental and high-order modes for a complicated spoof SPP structure, which have good agreements with the simulated results. Meanwhile, the calculated near fields also match the simulated and measured results well.